1. Field of the Invention
The present invention relates to an energization control apparatus that controls energization to a plurality of loads coupled in parallel.
2. Description of the Related Art
JP-A-55-106832 (corresponding to U.S. Pat. No. 4,259,659) discloses a flasher apparatus that includes a direction indicator for a vehicle as a plurality of loads coupled in parallel. The apparatus further includes a circuit for detecting an excessive current so as to detect a short fault of the direction indicator. The apparatus prohibits a detection of an excessive current for a predetermined period since energization to the direction indicator is started so as to distinguish an excessive current due to a short fault and an inrush current at the start of energization.
JP-A-2000-245054 discloses a circuit for detecting a short or a disconnection of a load. In addition, each of JP-A-2007-15654 and JP-A-2009-241665 discloses an apparatus for detecting a disconnection of a load, and the apparatus compensates a threshold value for determining a disconnection.
In the apparatuses described in the above-described documents, influence of an inrush current to a disconnection detection is not considered. Thus, a disconnection may be detected by error due to the inrush current.
For example, in a case where a disconnection of a load is detected based on a supply current to a plurality of loads coupled in parallel, it is required to detect a decrement of the supply current to a load group. However, an inrush current at the start of energization may cover the decrement of the supply current due to a disconnection. Thus, a normal determination may be made even when a disconnection occurs. In addition, even after a disconnection is detected, a temporary inrush current may cause a normal determination.
In order to reduce influence of an inrush current, a supply current may be detected at a predetermined period since energization is started, and the detected supply current may be compared with a threshold value for detecting a disconnection. However, the above-described method cannot detect a decrement of the supply current after the supply current is detected.
In an energization control apparatus for a direction indicator for a vehicle, when a disconnection is detected, a blink period is shortened so as to inform a user. In this case, even when a disconnection occurs in a part of loads, the energization control apparatus needs to energize the other part of loads with a short period. However, when a disconnection is detected based on a disappearance of the inrush current, the direction indicator may be forcibly put out before a required lighting period elapses.